Tag Archives: metamaterials

I don’t often get a chance to feature Greece here but an April 4, 2016 news item on tornos news (and also on ANAmpa: Athens News Agency [and] Macedonian Press Agency) provides an opportunity,

Greece’s Alternate Minister for Research and Innovation Costas Fotakis and Russian Federation Deputy Minister for Education and Science Ludmila Ogorodova on Friday [April 1, 2016] signed an agreement for cooperation between the two countries in specialist new technologies, such as quantum technology, nanotechnology and related areas.

According to an announcement, the agreement covers four innovative applications in quantum nano-electronics, nanophotonics, quantum information-communication and metamaterials. It extends an invitation to research and technology centres, universities and even public and private research companies to submit proposals in the area of quantum technologies by the end of next June. It envisages financing of up to one million euros in each of the four proposed areas, for programmes to be implemented over 24-36 months.

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In spite of the difficult conditions created by the economic crisis, Greece has research centres that have achieved international acclaim and excellence in the emerging field of quantum technology, …

So it seems Greece is supplying the quantum expertise and Russia the nanotechnology expertise. It’s a bit surprising that Anatoly Chubais isn’t mentioned since every reference that I’ve ever seen to Russian nanotechnology includes his name as the head of Russia’s state-funded RUSNANO (Russian Nanotechnology Corporation).

This property comes from their geometric substructure, which when stationary looks like a series of connected squares. When the squares turn relative to each other, however, the material’s density lowers but its thickness increases, allowing it to grow when stretched.

But this twisting means that the materials lose their original shape as they expand. So Ahmad Rafsanjani and Damiano Pasini of McGill University in Montreal, Canada, set out to create a material that would grow when stretched yet keep its form.

To do this, they turned to a beautiful kind of geometry.

“There is a huge library of geometries when you look at Islamic architectures,” says Rafsanjani. The team picked their design from the walls of the Kharraqan towers, two mausoleums built in 1067 and 1093 in the plains in northern Iran.

Both Webb’s and Hall’s articles are embedded with images of the architecture. There’s also a New Scientist video demonstrating stretchability,

Researchers at the University of Pennsylvania have now created the thinnest plates that can be picked up and manipulated by hand.

Despite being thousands of times thinner than a sheet of paper and hundreds of times thinner than household cling wrap or aluminum foil, their corrugated plates of aluminum oxide spring back to their original shape after being bent and twisted.

Like cling wrap, comparably thin materials immediately curl up on themselves and get stuck in deformed shapes if they are not stretched on a frame or backed by another material.

Being able to stay in shape without additional support would allow this material, and others designed on its principles, to be used in aviation and other structural applications where low weight is at a premium.

Here’s an image provided by the researchers,

Caption: Even though they are less than 100 nanometers thick, the researchers’ plates are strong enough to be picked up by hand and retain their shape after being bent and squeezed. Credit: University of Pennsylvania

“Materials on the nanoscale are often much stronger than you’d expect, but they can be hard to use on the macroscale” Bargatin [Igor Bargatin, Assistant Professor] said. “We’ve essentially created a freestanding plate that has nanoscale thickness but is big enough to be handled by hand. That hasn’t been done before.”

Graphene, which can be as thin as a single atom of carbon, has been the poster-child for ultra-thin materials since it’s discovery won the Nobel Prize in Physics in 2010. Graphene is prized for its electrical properties, but its mechanical strength is also very appealing, especially if it could stand on its own. However, graphene and other atomically thin films typically need to be stretched like a canvas in a frame, or even mounted on a backing, to prevent them from curling or clumping up on their own.

“The problem is that frames are heavy, making it impossible to use the intrinsically low weight of these ultra-thin films,” Bargatin said. “Our idea was to use corrugation instead of a frame. That means the structures we make are no longer completely planar, instead, they have a three-dimensional shape that looks like a honeycomb, but they are flat and contiguous and completely freestanding.”

“It’s like an egg carton, but on the nanoscale,” said Purohit. [Prashant Purohit, associate professor]

The researchers’ plates are between 25 and 100 nanometers thick and are made of aluminum oxide, which is deposited one atomic layer at a time to achieve precise control of thickness and their distinctive honeycomb shape.

“Aluminum oxide is actually a ceramic, so something that is ordinarily pretty brittle,” Bargatin said. “You would expect it, from daily experience, to crack very easily. But the plates bend, twist, deform and recover their shape in such a way that you would think they are made out of plastic. The first time we saw it, I could hardly believe it.”

Once finished, the plates’ corrugation provides enhanced stiffness. When held from one end, similarly thin films would readily bend or sag, while the honeycomb plates remain rigid. This guards against the common flaw in un-patterned thin films, where they curl up on themselves.

This ease of deformation is tied to another behavior that makes ultra-thin films hard to use outside controlled conditions: they have the tendency to conform to the shape of any surface and stick to it due to Van der Waals forces. Once stuck, they are hard to remove without damaging them.

Totally flat films are also particularly susceptible to tears or cracks, which can quickly propagate across the entire material.

“If a crack appears in our plates, however, it doesn’t go all the way through the structure,” Davami [Keivan Davami, postdoctoral scholar] said. “It usually stops when it gets to one of the vertical walls of the corrugation.”

The corrugated pattern of the plates is an example of a relatively new field of research: mechanical metamaterials. Like their electromagnetic counterparts, mechanical metamaterials achieve otherwise impossible properties from the careful arrangement of nanoscale features. In mechanical metamaterials’ case, these properties are things like stiffness and strength, rather than their ability to manipulate electromagnetic waves.

Other existing examples of mechanical metamaterials include “nanotrusses,” which are exceptionally lightweight and robust three-dimensional scaffolds made out of nanoscale tubes. The Penn researchers’ plates take the concept of mechanical metamaterials a step further, using corrugation to achieve similar robustness in a plate form and without the holes found in lattice structures.

That combination of traits could be used to make wings for insect-inspired flying robots, or in other applications where the combination of ultra-low thickness and mechanical robustness is critical.

“The wings of insects are a few microns thick, and can’t thinner because they’re made of cells,” Bargatin said. “The thinnest man-made wing material I know of is made by depositing a Mylar film on a frame, and it’s about half a micron thick. Our plates can be ten or more times thinner than that, and don’t need a frame at all. As a result, they weigh as little as than a tenth of a gram per square meter.”

To be more accurate, this is a step forward towards photonic circuits according to an Aug. 20, 2014 news item on Azonano,

The invention of fibre optics revolutionized the way we share information, allowing us to transmit data at volumes and speeds we’d only previously dreamed of. Now, electrical engineering researchers at the University of Alberta are breaking another barrier, designing nano-optical cables small enough to replace the copper wiring on computer chips.

This could result in radical increases in computing speeds and reduced energy use by electronic devices.

“We’re already transmitting data from continent to continent using fibre optics, but the killer application is using this inside chips for interconnects—that is the Holy Grail,” says Zubin Jacob, an electrical engineering professor leading the research. “What we’ve done is come up with a fundamentally new way of confining light to the nano scale.”

At present, the diameter of fibre optic cables is limited to about one thousandth of a millimetre. Cables designed by graduate student Saman Jahani and Jacob are 10 times smaller—small enough to replace copper wiring still used on computer chips. (To put that into perspective, a dime is about one millimetre thick.)

Jahani and Jacob have used metamaterials to redefine the textbook phenomenon of total internal reflection, discovered 400 years ago by German scientist Johannes Kepler while working on telescopes.

Researchers around the world have been stymied in their efforts to develop effective fibre optics at smaller sizes. One popular solution has been reflective metallic claddings that keep light waves inside the cables. But the biggest hurdle is increased temperatures: metal causes problems after a certain point.

“If you use metal, a lot of light gets converted to heat. That has been the major stumbling block. Light gets converted to heat and the information literally burns up—it’s lost.”

Jacob and Jahani have designed a new, non-metallic metamaterial that enables them to “compress” and contain light waves in the smaller cables without creating heat, slowing the signal or losing data. …

The team’s research is funded by the Natural Sciences and Engineering Research Council of Canada and the Helmholtz-Alberta Initiative.

Jacob and Jahani are now building the metamaterials on a silicon chip to outperform current light confining strategies used in industry.

Given that this work is being performed at the nanoscale and these scientists are located within the Canadian university which houses Canada’s National Institute of Nanotechnology (NINT), the absence of any mention of the NINT comes as a surprise (more about this organization after the link to the researchers’ paper).

In a search for the NINT’s website I found this summary at the University of Alberta’s NINT webpage,

The National Institute for Nanotechnology (NINT) was established in 2001 and is operated as a partnership between the National Research Council and the University of Alberta. Many NINT researchers are affiliated with both the National Research Council and University of Alberta.

NINT is a unique, integrated, multidisciplinary institute involving researchers from fields such as physics, chemistry, engineering, biology, informatics, pharmacy, and medicine. The main focus of the research being done at NINT is the integration of nano-scale devices and materials into complex nanosystems that can be put to practical use. Nanotechnology is a relatively new field of research, so people at NINT are working to discover “design rules” for nanotechnology and to develop platforms for building nanosystems and materials that can be constructed and programmed for a particular application. NINT aims to increase knowledge and support innovation in the area of nanotechnology, as well as to create work that will have long-term relevance and value for Alberta and Canada.

…

The University of Alberta’s NINT webpage also offers a link to the NINT’s latest rebranded website, The failure to mention the NINT gets more curious when looking at a description of NINT’s programmes one of which is hybrid nanoelectronics (Note: A link has been removed),

Hybrid NanoElectronics provide revolutionary electronic functions that may be utilized by industry through creating circuits that operate using mechanisms unique to the nanoscale. This may include functions that are not possible with conventional circuitry to provide smaller, faster and more energy-efficient components, and extend the development of electronics beyond the end of the roadmap.

After looking at a list of the researchers affiliated with the NINT, it’s apparent that neither Jahani or Jacob are part of that team. Perhaps they have preferred to work independently of the NINT ,which is one of the Canada National Research Council’s institutes.

This story comes from Nova Scotia although you wouldn’t know it if you’d only read the June 5, 2014 news item on Azonano,

Lamda Guard, a company based in Atlantic Canada, has signed an agreement with leading aircraft manufacturer Airbus to test a breakthrough innovation designed to deflect unwanted bright light or laser sources from impacting jetliner flight paths, and causing pilot disorientation or injury.

A June 4, 2014 news release (either from Lamda Guard.com or MTI [metamaterial.com]; Note: More about the multiple webspaces later] and there’s a PDF version here), which originated the news item, provides a little more information about the technology and the perspectives from various stakeholders

Lamda Guard’s innovative thin films utilize metamaterial technology on cockpit windscreens to selectively block and control light coming from any angle even at the highest power levels. “Today marks a milestone in optical applications of nano-composites,” said George Palikaras, President and CEO of Lamda Guard. “Through our collaboration with Airbus we are working to introduce our metamaterial technology, for the first time, as a solution to laser interference in the aviation industry.” The announcement today comes within weeks of the release of an FBI [US Federal Bureau of Investigation] report citing 3,960 aircraft laser strikes in the US in 2013 according to the Federal Aviation Authority (FAA).

Senior Vice President of Innovation Yann Barbaux stated: “At Airbus, we are always on the lookout for new ideas coming from innovative SMEs [small to medium enterprises], such as Lamda Guard. We are very pleased to explore together the potential application of this solution to our aircraft, for the benefit of our customers.”

Over the past year Lamda Guard has been working with the research community at the University of Moncton and the University of New Brunswick, as well as stakeholders, investors and funders to highlight the benefits of nano-composites. The Atlantic Canada Opportunities Agency (ACOA) in particular has played an important role in Lamda Guard’s research and development efforts. In 2012, ACOA assisted Lamda Guard with technology commercialization and recently upgraded its contribution to $500,000 to further assist the company in developing and manufacturing its products for the aviation industry.

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The Lamda Guard Airbus partnership marks the first time an optical metamaterial nano-composite has been applied on a large-scale surface.

A metamaterial typically consists of a multitude of structured unit cells that are comprised of multiple individual elements, which are referred to as meta-atoms. The individual elements are assembled from conventional microscopic materials such as metals and/or plastics, which are arranged in periodic patterns.

…

MTI’s precisely designed structures are developed with proprietary algorithms, producing a new generation of optical products that are built in state-of-the-art thin film nano-fabrication labs. MTI’s proprietary software accurately predicts the desired design pattern to generate a unique material that meets customer specifications. MTI’s sleek designs mean manufacturers can reduce their cost of materials significantly while increasing performance, e.g. by increasing the light output of an LED bulb or increasing the absorption of light in a solar panel.

Multiple webspaces and presences

While Lamda Guard has a .com presence, you will find yourself on the metamaterial.com website in the Lamda Guard webspace (I suppose you could also call it a subsite) once you start clicking for more information. In fact, MTI owns three Lamda companies as per this description from the Our Company webpage on the MTI (metamaterial.com) website (Note: Links have been removed),

MTI is an advanced materials and systems engineering company developing and commercializing innovative optical solutions. The company’s core team has over 200 years of combined experience at the forefront of the design and implementation of metamaterials, making MTI a pioneer in bridging the gap between the theoretical and the possible.

MTI specializes in metamaterials, nanotechnology, theoretical and computational electromagnetics. The company’s in-house expertise enables the rapid development of a wide array of metamaterial applications, covering a diverse range of markets.

MTI’s technologies are adaptable and can be custom-designed to suit an industry manufacturer’s specifications allowing for scalability and rapid prototyping with minimum overheads. MTI provides access to world class nano-composite research and development, including specialty, as well as customized, products and licensing of its proprietary solutions to customers ranging from government to private companies.

MTI has three wholly owned subsidiaries:

Lamda Guard Inc. which develops advanced filters to block out selected parts of the light spectrum, protecting the eyes from lasers or other sources of hazardous light.

Lamda Lux Inc. technology increases the delivered lumens and reduces the cost of thermal management of LED lighting.

Interestingly, the Lamda Guard Management team‘s (in the Lamda Guard webspace) Chief Science Officer, Dr. Themos Kallos, and Chief Intellectual Property Officer, Dr. Quinton Fivelman, both appear to reside in the UK (assuming I looked at the correct LinkedIn profiles). Coincidentally, MTI’s contact page lists the company’s headquarters as being in Nova Scotia but Sales, Research and Development would seem to be located in the UK.

Presumably, this company is maximizing its access to government grants and tax incentives in both the UK and Canada. The deal with the Airbus suggests that this has been a successful strategy possibly leading to commercialized technology and, hopefully, jobs.

University of Toronto researchers, Michael Selvanayagam and George V. Eleftheriades, have offered a popular summary of their work. from the popular summary (on the website where they’ve published their academic paper),

We “see” a physical object by detecting electromagnetic waves scattered from the object. A device that can “correct” or cancel that scattering would take the notion of a magic invisibility cloak from the realm of science fiction to reality. In fact, such physical devices already exist, accomplishing their feat based on metamaterials that bend light around the object to be cloaked, “correcting” the scattering. Designing metamaterials with the right light-bending properties for this purpose is, however, quite challenging, and the designs often require a thick “cloak.” An alternative approach to this problem is “active cloaking”: surrounding the object to be cloaked with electromagnetic sources that are carefully tuned to cancel the electromagnetic field scattered by the object. In this work, we demonstrate the first experimental realization of such a thin active cloak for microwaves.

The sources we have used are specially designed antennas and phase shifters, which can be configured into thin layers with flexibility in shape. We have succeeded in cloaking a sizable metallic cylinder by properly tuning the phase of the radiation from the antennas so that the radiation cancels the field scattered by the cylinder. We have gone a step further than cloaking and have also demonstrated how the object can be disguised as another object by tuning the antennas in a controlled way. The catch with active cloaking, however, is that knowledge of the incident field is required to tune the antennas. To tackle this issue, we have discussed some potential solutions that also utilize the antennas as sensors to detect the incident field.

Future work along this line will aim to extend the bandwidth of the cloak (with respect to pulsed incident fields) as well as design active cloaks that can adaptively respond to an incident field.

Professor George Eleftheriades and PhD student Michael Selvanayagam have designed and tested a new approach to cloaking — by surrounding an object with small antennas that collectively radiate an electromagnetic field. The radiated field cancels out any waves scattering off the cloaked object. Their paper ‘Experimental demonstration of active electromagnetic cloaking’ appears today in the journal Physical Review X.

“We’ve taken an electrical engineering approach, but that’s what we are excited about,” says Eleftheriades. “It’s very practical.”

Picture a mailbox sitting on the street. When light hits the mailbox and bounces back into your eyes, you see the mailbox. When radio waves hit the mailbox and bounce back to your radar detector, you detect the mailbox. Eleftheriades and Selvanyagam’s system wraps the mailbox in a layer of tiny antennas that radiate a field away from the box, cancelling out any waves that would bounce back. In this way, the mailbox becomes undetectable to radar.

“We’ve demonstrated a different way of doing it,” says Eleftheriades. “It’s very simple: instead of surrounding what you’re trying to cloak with a thick metamaterial shell, we surround it with one layer of tiny antennas, and this layer radiates back a field that cancels the reflections from the object.”

Their experimental demonstration effectively cloaked a metal cylinder from radio waves using one layer of loop antennas. The system can be scaled up to cloak larger objects using more loops, and Eleftheriades says the loops could become printed and flat, like a blanket or skin.

For now, the antenna loops must be manually attuned to the electromagnetic frequency they need to cancel. But in future, researchers say, they could function both as sensors and active antennas, adjusting to different waves in real time, much like the technology behind noise-cancelling headphones.

Work on developing a functional invisibility cloak began around 2006, but early systems were necessarily large and clunky – if you wanted to cloak a car, for example, in practice you would have to completely envelop the vehicle in many layers of metamaterials in order to effectively “shield” it from electromagnetic radiation. The sheer size and inflexibility of that approach makes it impractical for real-world uses.

Earlier attempts to make thin cloaks were not adaptive and active, and could work only for specific small objects.

The cloaking technology holds possiblities that go beyond obvious applications such as hiding military vehicles or conducting surveillance operations. For example, structures that interrupt signals from cellular base stations could be cloaked to allow signals to pass by freely.

The system can also alter the signature of a cloaked object, making it appear bigger, smaller, or even shifting it in space. And though their tests showed the cloaking system works with radio waves, re-tuning it to work with Terahertz (T-rays) or light waves could use the same principle as the necessary antenna technology matures.

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

The Dec. 19, 2012 news release on EurekAlert about a study published by researchers at Aalto University (Finland) describes a project where virus particles are combined with nanoparticles to create new metamaterials,

Scientists from Aalto University, Finland, have succeeded in organising virus particles, protein cages and nanoparticles into crystalline materials. These nanomaterials studied by the Finnish research group are important for applications in sensing, optics, electronics and drug delivery.

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… biohybrid superlattices of nanoparticles and proteins would allow the best features of both particle types to be combined. They would comprise the versatility of synthetic nanoparticles and the highly controlled assembly properties of biomolecules.

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The gold nanoparticles and viruses adopt a special kind of crystal structure. It does not correspond to any known atomic or molecular crystal structure and it has previously not been observed with nano-sized particles.

Virus particles – the old foes of mankind – can do much more than infect living organisms. Evolution has rendered them with the capability of highly controlled self-assembly properties. Ultimately, by utilising their building blocks we can bring multiple functions to hybrid materials that consist of both living and synthetic matter, Kostiainen [Mauri A. Kostiainen, postdoctoral researcher] trusts.

The article which has been published in Nature Nanotechnology is free,

From the YouTube page, here’s a description of what the video is demonstrating,

Aalto University-led research group shows that CCMV virus or ferritin protein cages can be used to guide the assembly of RNA molecules or iron oxide nanoparticles into three-dimensional binary superlattices. The lattices are formed through tuneable electrostatic interactions with charged gold nanoparticles.

Bravo and thank you to Kostiainen who seems to have written the news release and prepared all of the additional materials (image and video). There are university press offices that could take lessons from Kostiainen’s efforts to communicate about the work.

Sometimes one experiences a frisson (shiver) when reading about a piece of research. Let’s see how you do with this Dec. 4, 2012 news item on Nanowerk,

A bit reminiscent of the Terminator T-1000, a new material created by Cornell researchers is so soft that it can flow like a liquid and then, strangely, return to its original shape.

Rather than liquid metal, it is a hydrogel, a mesh of organic molecules with many small empty spaces that can absorb water like a sponge. It qualifies as a “metamaterial” with properties not found in nature and may be the first organic metamaterial with mechanical meta-properties.

Hydrogels have already been considered for use in drug delivery — the spaces can be filled with drugs that release slowly as the gel biodegrades — and as frameworks for tissue rebuilding. The ability to form a gel into a desired shape further expands the possibilities. For example, a drug-infused gel could be formed to exactly fit the space inside a wound.

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The new hydrogel is made of synthetic DNA. In addition to being the stuff genes are made of, DNA can serve as a building block for self-assembling materials. Single strands of DNA will lock onto other single stands that have complementary coding, like tiny organic Legos. By synthesizing DNA with carefully arranged complementary sections Luo’s [Dan Luo, professor of biological and environmental engineering] research team previously created short stands that link into shapes such as crosses or Y’s, which in turn join at the ends to form meshlike structures to form the first successful all-DNA hydrogel. Trying a new approach, they mixed synthetic DNA with enzymes that cause DNA to self-replicate and to extend itself into long chains, to make a hydrogel without DNA linkages.

“During this process they entangle, and the entanglement produces a 3-D network,” Luo explained. But the result was not what they expected: The hydrogel they made flows like a liquid, but when placed in water returns to the shape of the container in which it was formed.

“This was not by design,” Luo said.

See the material for yourself,

Hydrogels made in the form of the letters D, N and A collapse into a liquid-like state on their own but return to the original shape when surrounded by water Provided/Luo Lab

Nature Nanotechnology published the team’s research online Dec. 2, 2012 and, unusually, the article is open access (at least for now),

Depending on your reading interests and time available, Bill Steele’s Cornell University article has more detail than I’ve provided here or you can check out the well illustrated article in Nature Nanotechnology. As these things go, it’s quite readable as you can see with the abstract (Note: I have removed footnotes),

Metamaterials are artificial substances that are structurally engineered to have properties not typically found in nature. To date, almost all metamaterials have been made from inorganic materials such as silicon and copper, which have unusual electromagnetic or acoustic properties that allow them to be used, for example, as invisible cloaks superlenses or super absorbers for sound. Here, we show that metamaterials with unusual mechanical properties can be prepared using DNA as a building block. We used a polymerase enzyme to elongate DNA chains and weave them non-covalently into a hydrogel. The resulting material, which we term a meta-hydrogel, has liquid-like properties when taken out of water and solid-like properties when in water. Moreover, upon the addition of water, and after complete deformation, the hydrogel can be made to return to its original shape. The meta-hydrogel has a hierarchical internal structure and, as an example of its potential applications, we use it to create an electric circuit that uses water as a switch.

For anyone not familiar with the Terminator movies, here’s an essay in Wikipedia about the ‘franchise’. Pay special note to the second movie in the series, Terminator 2: Judgment Day which introduced a robot (played by Robert Patrick) that could morph from a liquidlike state into various lethal entities.

First, it might be a good idea to define chirality. From the Lawrence Berkeley National Laboratory (Berkeley Lab) July 10, 2012 news release by LynnYarris,

Chirality is the distinct left/right orientation or “handedness” of some types of molecules, meaning the molecule can take one of two mirror image forms. The right-handed and left-handed forms of such molecules, called “enantiomers,” can exhibit strikingly different properties. For example, one enantiomer of the chiral molecule limonene smells of lemon, the other smells of orange. The ability to observe or even switch the chirality of molecules using terahertz (trillion-cycles-per-second) electromagnetic radiation is a much coveted asset in the world of high technology.

As for why anyone would want to flip molecules back and forth between left- and right-handedness (from the news release),

A multi-institutional team of researchers that included scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has created the first artificial molecules whose chirality can be rapidly switched from a right-handed to a left-handed orientation with a beam of light. This holds potentially important possibilities for the application of terahertz technologies across a wide range of fields, including reduced energy use for data-processing, homeland security and ultrahigh-speed communications.

Working with terahertz (THz) metamaterials engineered from nanometer-sized gold strips with air as the dielectric – Zhang [Xiang Zhang, one of the leaders of this research and a principal investigator with Berkeley Lab’s Materials Sciences Division] and his colleagues fashioned a delicate artificial chiral molecule which they then incorporated with a photoactive silicon medium. Through photoexcitation of their metamolecules with an external beam of light, the researchers observed handedness flipping in the form of circularly polarized emitted THz light. Furthermore, the photoexcitation enabled this chirality flipping and the circular polarization of THz light to be dynamically controlled.

“In contrast to previous demonstrations where chirality was merely switched on or off in metamaterials using photoelectric stimulation, we used an optical switch to actually reverse the chirality of our THz metamolecules,” Zhang says.

The researchers describe in more detail the potential for this new technique,

“The observed giant switchable chirality we can engineer into our metamaterials provides a viable approach towards creating high performance polarimetric devices that are largely not available at terahertz frequencies,” says corresponding author Antoinette Taylor. “This frequency range is particularly interesting because it uniquely reveals information about physical phenomena such as the interactions between or within biologically relevant molecules, and may enable control of electronic states in novel material systems, such as cyclotron resonances in graphene and topological insulators.”

Taylor and her co-authors say that the general design principle of their optically switchable chiral THz metamolecules is not limited to handedness switching but could also be applied to the dynamic reversing of other electromagnetic properties.

From what I understand metamaterials are very expensive and difficult to produce which means this exciting advance is likely to remain in the laboratory of at least 10 years.